I beg to disagree about the disadvantages. An important one is that you cannot easily update shared libraries globally. This is a problem with things like libssl or similar. Another disadvantage is the added complexity both wrt. to operation but also in general the amount of code running. It can also be problematic that many people just run containers without doing any auditing. In general containers are pretty opaque compared to os packaged software which is usually compiled individually for the os.

This being said, systemd offers a lot of isolation features that allows similar isolation to containers but without having to deal with docker.